引言在秘鲁东南部Macusani附近出露了晚第三纪喷发的强铝过饱和的酸性火山岩。对这些岩石虽然在一些文献中(如Francis 1959b、Barn(?)s等1970、Erench等1978、Noble等1982)已述及,但在近来的有关“S-型”花岗岩和稀有元素富集的长英质火成岩的论述中,这类岩石却常常被忽视。在此我们在强调铝过饱和流纹质火山岩体积之大的同时,还列举了这些岩石的放射性年龄、岩相学、矿物学、化学和同位素学方面的新资料,并对这类岩石的岩石学及其区域背景进行了初步讨论。 INTRODUCTION Strong aluminous over-saturated acidic volcanic rocks erupted in the late Tertiary in the vicinity of Macusani, south-eastern Peru. Although these rocks have been described in some literatures (eg Francis 1959b, Barn (?) S et al 1970, Erench et al 1978, Noble et al 1982), recent literature on “S-type” granites and their enrichment In the discussion of felsic igneous rocks, such rocks are often overlooked. While highlighting the large volume of Al-saturated rhyolitic volcanic rocks, we also present new information on radiogenic age, lithology, mineralogy, chemistry and isotopes of these rocks, Study and its regional background for a preliminary discussion.